Device for cooling and cleaning of grinding wheels

ABSTRACT

A DEVICE FOR THE COOLING AND CLEANING OF GRINDING WHEELS DURING THE GRINDING OPERATION BY MEANS OF A PRESSURIZED FLUID APPLIED THROUGH NOZZLES TO THE GRINDING SURFACES OF THE GRINDING WHEEL. A MULTITUDE OF NOZZLES ARE PROVIDED IN GNERALLY U-SHAPED BLOCK AND ADAPTED TO DISCHARGE A JET OF A HIGH KINETIC ENERGY WHICH IMPINGES UPON THE GRINDING SURFACES OF THE GRINDING WHEEL. ADDITIONAL MEANS MAY BE PROVIDED FOR REDUCING THE RESISTANCE CAUSED BY AIR TURBULENCE BETWEEN THE NOZZLES AND THE GRINDING WHEEL.

March 9, 1971 R. BLOHM ETAL DEVICE FOR COOLING AND CLEANING OF GRINDING WHEELS Fild Jan.

United States Patent 3,568,377 DEVICE FOR COOLING AND CLEANING 0F GRINDING WHEELS Robert Blohm, 63 Kampchaussee, 80 Hamburg, Germany,

and Wlodzimierz Sawluk, 82 Falkenried, 20 Hamburg,

Germany Filed Jan. 2, 1969, Ser. No. 788,366 Claims priority, application Germany, Jan. 9, 1968, P 16 52 003.9 Int. Cl. B24b 55/00 US. Cl. 51-262 8 Claims ABSTRACT OF THE DISCLOSURE A device for the cooling and cleaning of grinding wheels during the grinding operation by means of a pressurized fluid applied through nozzles to the grinding surfaces of the grinding wheel. A multitude of nozzles are provided in a generally U-shaped block and adapted to discharge a jet of a high kinetic energy which impinges upon the grinding surfaces of the grinding wheel. Additional means may be provided for reducing the resistance caused by air turbulence between the nozzles and the grinding wheel.

This invention relates to a'device for the cooling and cleaning of grinding wheels during the grinding operation by means of pressure fluid fed through nozzles to the grinding surfaces of the grinding wheel.

Grinding wheels are, in a known manner, composed of a granular abrasive and a bonding material. The abrasive usually consists of very hard crystals, particularly of corundum, i.e. aluminium oxide, or of carborundum which is silicon carbide, to mention only the most important ones. The bonding may be based on ceramic, mineral, vegetable and plastic bonding such as by hardenable resins.

The sizes of the granules and the hardness and the kind of bonding determine the suitability of a grinding tool for a certain application and for working with a certain material.

The bonding hardness will be determined primarily in correspondence with the hardness of the material to be worked. A hard material requires soft wheels so that the blunted granules may split or quickly break loose and the grinding wheel does not become clogged or smeared. For soft materials harder wheels may be utilized, with these, however, the hazard of the wheel becoming clogged or smeared is particularly high.

It is already known to cool the grinding surfaces of grinding wheels of this kind during the grinding operation by means of a pressure fluid applied through nozzles. In such an arrangement the nozzles are adjusted in an approximately tangential direction with respect to the grinding wheel so that the pressure fluid may reach that area of the grinding wheel which is at any moment in engagement with the material to be ground. When feeding pressure fluid in this way the object of cooling the wheel will be primarily achieved, necessitating only moderate pressures for the pressure fluid.

It is a principal object of the present invention to provide means for not only cooling but also cleaning and, to a certain degree, sharpening the grinding surface portion of the grinding wheel by means of a ressurized liquid. It is known to combine the grinding operation with a certain degree of a self-sharpening effect. The blunted granules break out under the influence of the higher forces acting on them, exposing thereby new cutting granules which will take over the load of the grinding. This self-sharpening effect increases with increasing hardness of the material. When working on a soft material ice there exists the hazard that the grinding surface portion of the grinding wheel becomes clogged or, in other words, smeared by the material being worked, requiring frequent finishing or dressing of the grinding wheel. For this reason, very soft materials practically cannot be treated by grinding.

It is a further object of the invention to provide a device for cleaning and cooling of grinding wheels which is characterized in that the fluid may be applied through a multitude of nozzles being arranged at substantially right angles to the grinding surface whereby the fluid has a high kinetic energy and impinges on the grinding surface of the grinding wheel within an area which is positioned outside the grindng wheel area at any moment being in engagement with the workpiece. In this way, the grinding wheels will persent a completely cleaned and sharp grinding surface for coming into engagement with the workpiece upon every revolution of the wheel, thus allowing the grinding of relatively large areas at a high feeding speed and depth of engagement (full grinding) without requiring dressing of the grinding wheel. The invention also allows to grind soft materials over substan tially longer working periods and, additionally, the grinding of extremely soft materials such as brass or copper will be possible, hitherto not manageable by grinding.

Smooth nozzles, that is nozzles which are smooth in the hydrodynamic sense, discharge relatively far-reaching concentrated jets in which only a minor portion of the fluid being discharged from the nozzle becomes atomized, provided the grinding surface of the grinding wheel is spaced as closely as possible from the outlet ort of the nozzle.

In accordance with the present invention it may be preferable to convert the fluid into a mist or fog before it impinges on the grinding surface of the grinding wheel. A correspondingly arranged embodiment of the present invention allows to treat, ie to cool and clean, a large grinding surface by means of a relatively small number of nozzles.

For achieving this purpose fluid may be pressurized by known means and subsequently discharged by nozzles. As it is generally known, the fluid conduits must be shaped and arranged in such a way and include suitable baffles in order to produce spinning and turbulence by kinetic energy of the fluid, disintegrating in turn the jet due to the resulting centrifugal forces and splitting the fluid in the static ambient air due to the velocity difference, or squashing the fluid on an impact surface or the like. For practicing the present invention cone-shaped nozzles as well as nozzles producing flat jets may be utilized. It is even possible to utilize a rotating sprayer or atomizer, although the added constructional complications involved generally tend to make the arrangement of the rotating nozzle atomizers appear less desirable.

With still another embodiment of the present invention the conversion of the fluid into mist or fog may be obtained in another manner, likewise known by itself, this manner being characterized in that the fluid is applied by means of a nozzle which discharges a pressurized gas having a high velocity and draws along the fluid in the form of droplets or in atomized condition.

In general, any type of gas may be utilized, compressed air being the preferred gas because it is most readily available. Any other gas, particularly an inert gas such as nitrogen or carbon dioxide may be utilized. The additional cooling effect provided by an expanding pressurized gas may be particularly advantageous for atomizing fluid by means of pressurized gas. In this case the fluid normally will be maintained at barometric pressure. The invention, however, is not intended to be limited to this particular arrangement. When atomizing the fluid by means of pressurized gas the nozzle for discharging the pressurized gas and the feeding conduit for the fluid will be preferably arranged concentrically so that the fluid feeding conduit concentrically surrounds the nozzle or, inversely, a nozzle for the pressurized gas concentrically surrounds a fluid feeding conduit mounted concentrically in the interior of the nozzle, the nozzle, in the latter case, being arranged in the form of a ring channel or comprising a plurality of circularly arranged nozzles.

In an alternate embodiment of the invention the pressuriz'ed fluid is supplied to a plurality of nozzles from a supply chamber, the nozzle axis being directed at substantially right angles to the grinding surface. The diameter of each nozzle does not exceed 2 mm. Nozzles of this 'kind may be considered smooth, i.e. good nozzles in the hydrodynamic sense, only a small portion of the jet discharging from the nozzle becoming atomized. On the other hand, with this embodiment of the invention it is important that the nozzles should be spread as evenly as possible over the grinding surface portion of the grinding wheel.

The pressure of the pressure fluid depends to a high degree on the diameter of the nozzle ports but also depends naturally on the hardness of the bonding, the size of the abrasive granules and the material of the workpiece. If the nozzle diameter is 1 mm., a suitable pressure of the pressure fluid would be kp./cm. It may also be preferable to apply higher pressures in the range of several hundred kp./cm. A similar advantage may be gained if the nozzle diameters are appreciably below a value of 1 mm.

The orifices of the nozzles should be arranged as closely as possible to the grinding surfaces 'of the grinding wheel. As a general rule, this spacing would be only 1 mm. or a few millimeters.

In accordance with the present invention the maximum spacing of the orifices of the nozzles equals ten times the diameter of the nozzle orifices, all of the grinding surface of the wheel being substantially covered by nozzle orifices.

In a suitable embodiment of the invention the nozzles are arranged within a block which is U-shaped, straddles the circumference of the grinding wheel and is provided with a supply chamber to which a pressure source may be connected, the supply chamber communicating with the nozzle orifices. This block may be made of a solid block of a rigid material which can be readily machined such as a solid block of ingot steel. In a block of this type a large number of precise nozzle orifices may be most conveniently provided by means of metal cutting techniques. At the same time, a block of this type provides a suflicient degree of rigidity and tightness even at high pressures of the fluid medium.

It may be desirable to provide a multitude of these blocks around the free circumferential portion of the grinding wheel. This particularly applies to those cases in which relatively low pressures such as 20 kp./cm. are applied and the diameter of the nozzle orifices is 1 mm. Such a tandem arrangement of several blocks provides the added advantage of requiring only relatively small blocks which may be provided at small expense with a sufiicient number of nozzle bores.

It is an important feature of the invention that the high speed fluid jets leaving the nozzles reach the surface of the grinding wheel quickly and in the shortest path. It has been observed that the usually rough and fissured surface of the grinding wheel rotating at high speed (the tangential velocity usually is within a range of approximately 15-45 m./sec. but may be increased in special applications up to approximately 90 m./sec.) drags along an air layer so that a considerable fraction of the fluid jet which, in accordance with the invention is directed substantially perpendicularly to the grinding surface of the wheel, will be needed for penetrating this air layer and therefore is lost for the effect desired by the present invention.

The present invention, therefore, proposed to provide a deflector in front of each block, the deflector facing the entrance side of the grinding wheel and being mounted in such a manner that the clearance (gap) between the grinding surface of the grinding wheel and the edge of the deflector which is directed towards the grinding wheel is kept to a minimum. It may even be desirable to provide a device for removing the air along this edge of the deflector by suction with the aid of a vacuum source.

An exemplary embodiment of the invention will be described with reference to the appended drawing in which FIG. 1 shows a cross-sectional view through a cleaning and cooling device in accordance with the present invention, along the axis of the grinding wheel and along the line AA of FIGS. 3 and 4;

FIG. 2 is a top plan view of the device of FIG. 1;

FIG. 3 is an elevational view of the device of FIGS. 1 and 2;

FIG. 4 is an elevational view, similar to FIG. 3, in a reduced scale, and shows the distribution of a plurality of cleaning and cooling devices in accordance with the invention, along the larger portion of the circumference of the grinding wheel.

In the figures of the drawing the reference 1 designates a grinding wheel rotating in the sense indicated by the arrow 17 and grinding a workpiece 14 along the cutting path w. A plurality of cleaning and cooling devices are provided on the circumferential portion of the grinding wheel which lies outside the cutting path w. In the present embodiment these devices are in the form of a block designated by the reference 2. The block 2 may be more clearly seen in the FIGS. 1-3. In the exemplary embodiment, five blocks 2 are provided, these blocks being evenly spaced on that circumferential portion of the grinding wheel which lies outside the cutting path w. That portion may be called the circumferential engagement area of the cleaning and cooling fluid and is indicated by the broken line 15 in FIG. 4.

As may be seen from FIGS. 1-3, every one of the blocks 2 has the shape of a U, the arms of which straddle thecircumference of the grinding wheel 1. The crosspiece of the U-shaped block 2 is provided with a bore 3 which is open on one end and may be tightly sealed at this end by a screw 10. The two arms of the U-shaped block 2 are each provided with a bore '4, 5 respectively, each of these bores being likewise tightly sealed from the outside by a screw 10. The bores 4, 5 each include a right angle with the bore 3. This right angles is determined by the shape of the grinding wheel 1 and does not constitute a part of the present invention.

The supply chamber formed by the bores 3, 4 and 5 is supplied with pressurized cooling and cleaning fluid such as an emulsion or suspension of oil in water by means of a conduit 11. The direction of the fluid entering the supply chamber is indicated by the arrow 16.

A multitude of nozzles 6 which are preferably evenly and as closely as is practicable, spaced, interconnect the bore 3 with the outer surface of the block facing the grinding wheel 1 and are perpendicularly arranged to this surface. These nozzles 6 are (in the manner not shown in the drawing) conically tapered so that they have the smallest cross-sectioal area at the outlet side facing the grinding wheel. Additional nozzles 6 (not shown) may be arranged in a plane perpendicular to the plane of FIG. 1 of the drawing. These additional nozzles 6 may likewise communicate with the bore 3 and are substantially at right angles to the outer surface of the block facing the grinding wheel, i.e. to the circumferential area of the same.

Similar nozzles 7 communicate with the bore 5 and are arranged at right angles to a lateral surface of the grinding wheel 1. These nozzles are provided in that area of the grinding wheel in which the grinding wheel is intended to be utilized for grinding. For enabling the drilling of the nozzles 7, an auxiliary bore is provided in the block, enters the bore 5 and may be tightly sealed by a threaded plug 9.

In a similar manner, the bore 4 includes an auxiliary bore sealed by a threaded plug 9 and serving to facilitate drilling of the nozzles 8.

A deflector 13 is provided on the side of the block 2 at which the rotating wheel 1 enters the block. This deflector closely surrounds the surface of the grinding wheel 1, is attached by screws 12 to the block and has an U- shape which corresponds to the cross-sectional shape of the block. The deflector 13 serves to remove as far as may be achieved all air layers which are dragged along by the rotating grinding wheel before the fluid jets discharged from the nozzles 6, 7, 8 of the block 2 impinge upon the surface of the grinding wheel. The efliciency of the cleaning and cooling effect which may be achieved by the fluid jets impinging upon the surfaces of the grinding wheel will be increased if the air layer carried along by the grinding wheel can be more effectively removed or decreased.

What we claim is:

1. Apparatus for cleaning and cooling a rotating grinding wheel having an axis of rotation, a periphery and lateral sides, during the grinding of a workpiece comprising, in combination, a manifold block having a hollow interior supported adjacent the grinding wheel periphery having an inner surface of a length at least as great as the periphery width disposed toward the wheel periphery and closely spaced therefrom, a plurality of nozzles defined in said block constituting openings intersecting said inner surface and communicating with the interior of said block, said openings being arranged in said block to be disposed across the entire wheel periphery and radially disposed relative to the grinding wheel axis of rotation as to be perpendicular to the adjacent wheel periphery, and a pressurized fluid source communicating with said manifold block interior whereby pressurized fluid within said block is ejected against the entire wheel periphery through said openings to clean and cool the grinding wheel.

2. In apparatus for cleaning and cooling a rotating grinding wheel as in claim 1 wherein the diameter of said openings do not exceed 2 mm.

3. In apparatus for cleaning and cooling a rotating grinding wheel as in claim 2 wherein the maximum distance from the center of one opening to the center of adjacent openings is no greater than ten times .the diameter of said openings.

4. In apparatus for cleaning and cooling a rotating grinding wheel as in claim 1 wherein said manifold block is of a U-shape having a base portion and leg portions, said inner surface being defined on said base portion and said leg portions each including an inner surface closely disposed to a lateral side of the grinding wheel adjacent the periphery thereof, and a plurality of nozzle openings intersecting said leg portions inner surfaces communicating with said block interior and perpendicularly disposed to the adjacent wheel lateral side.

5. In apparatus for cleaning and cooling a rotating grinding wheel as in claim 1 wherein said openings are of a tapered configuration converging in a direction toward said inner surface.

6. In apparatus for cleaning and cooling a rotating grinding wheel as in claim 1, an air deflector defined on said block disposed adjacent the wheel periphery and located on said block toward the direction of rotation of the grinding wheel minimizing the entering of moving air adjacent the wheel periphery between said inner surface and wheel periphery.

7. In apparatus for cleaning and cooling a rotating grinding wheel as in claim 1 wherein said pressurized fluid is a liquid.

8. In apparatus for cleaning and cooling a rotating grinding wheel as in claim 1 wherein said pressurized fluid comprises a gas having particles of liquid entrained therein.

References Cited UNITED STATES PATENTS 1,413,060 4/1922 Roberts 51-262X 3,123,950 3/1964 Kuris et al. 51262X 3,123,951 3/1964 Kuris et al 51-262X 3,167,893 2/ 1965 Giardini et al. 51262X 3,177,627 4/1965 Guibert et al. 51-262X 3,256,647 6/ 1966 Hutton 51-267 WILLIAM R. ARMSTRONG, Primary Examiner 

